Hi, I have a 65 cutlass and have a problem with the car over charging. It has reached over 17 volts. Could this be a alternator or regulator issue? Thank you.

 

It's the regulator on the firewall.

 

That's what I thought originally and I took one off a good running car and still has the same problem. I also switched alternators with no luck. I'm at a loss.

 

How are you measuring the 17 Volts?
Since you measured the same thing before and after the parts swap, are you sure your measuring instrument is accurate?

 

Multimeter, tested normal on other cars

 

Did you try a different battery?

 

I will try a different battery, but how will that solve the problem?

 

Make sure the regulator is properly grounded . A poorly grounded regulator can cause an overcharging condition .
Measure the resistance between the negative battery post and the regulator body , shouldn't be more than a couple of ohms .

 

Make sure that the regulator's voltage sensor wire is well connected to the power post on the horn relay and to the terminal on the regulator.
It's the 3rd wire, Red, labeled "+".

- Eric

 

Are you measuring with the battery connected or disconnected? If you disconnect the battery while the engine is running the voltage can go extremely high. This can damage sensitive electronics in more modern vehicles with on-board computers. It can also damage aftermarket stereos if the voltage gets too high. Clean the battery terminals to make sure the system is solid.